I have a 2002 trailblazer chek eng. lt. on and reduced engine power.. why? on 2002 Chevrolet Trailblazer

I have replaced the plugs, fuel, and air filter. also fan clutch and water pump. it shows code p1481,1482, and 1484 on my little hand scanner. I talked with a tech who said that the 4.2L have a secondary air on the side of the block that may cause it but idk. If i clear the light it stays off for 10-15 miles then comes back on and the cruise cuts out. plz help